Application planning
6.6 Use in the motor protection area
3VL molded-case circuit breakers
76
System Manual, 03/2009, 110 0110 - 02 DS 01
Phase failure sensitivity
The "phase failure sensitivity" function is also integrated into the SENTRON VL circuit
breakers for motor protection. This ensures that the motor is reliably protected against
overheating if a phase interruption or a large fluctuation occurs.
The specified operational current IR is automatically reduced to 80% of the set value if the
r.m.s. values of the operational currents in the three phases differ by more than 50%.
Deviations of more than 50% mean the value of the current in the least loaded phase drops
to a level below 50% of the maximum loaded phase.
1,5
1.25x
,005
,002
,2
,02
,01
,05
,1
,5
Break time in s
TC=5
TC=10
TC=15
TC=20
TC=30
10 11x
8
6
5
4
3
2
5
2
50
20
10
100
200
10000
1000
5000
2000
500
2000
400
200
100
60
40
6
10
2
4
1
,001
20
1
A x
R
I
NSK-1134b
Figure 6-3
ETU with trip classes 5, 10, 15, 20, 30
Tripping characteristic curve for circuit breakers with electronic overcurrent trip unit.
I
cu
100 kA maximum at 415 V
7ULSSLQJWLPH
PLQ
W
7LPHDIWHU
Figure 6-4
Response time of the trip unit after overload release
① Without "thermal memory"
② with "thermal memory"
Summary of Contents for SENTRON 3VL series
Page 2: ......
Page 10: ...Table of contents 3VL molded case circuit breakers 10 System Manual 03 2009 110 0110 02 DS 01 ...
Page 350: ...Correction sheet 3VL molded case circuit breakers 350 System Manual 03 2009 110 0110 02 DS 01 ...
Page 358: ...Glossary 3VL molded case circuit breakers 358 System Manual 03 2009 110 0110 02 DS 01 ...
Page 359: ......